During the "Expedition Number 26", August 13-25, 1998, The
Cosmonaut - Researcher Yury Baturin had completed the Special Program of investigation,
which 1st time had the primary interest in the complex evaluation of the visual
system’s functional condition.

Cosmonaut -
Researcher Yury Baturin

Pre-started
classes and preparations

Authors of the
article from the left: L.Nesteruk, Y.Baturin, A.Prokofiev

Actually, the numerous studies of the different visual functions
were done in Outer Space as well as during the modeling of the flight conditions. This way
the primary attention was paid to the study of the following parameters of the visual
system: visual acuity, chromatic and contrast sensitivity, accommodation and convergence
(Y.P. Petrov, 1969, O.O. Riumin, 1980; A.P. Ginsburg, J. Vahderploeg., 1985; L.P. Zverev.,
I.G. Ovechkin., O.O. Riumin, 1996). It was found the visual acuity being highly stable and
does not change during the flight (E.V. Khrunov, L.S. Khachaturiantz, V.A. Popov, 1974).
The same data were obtained in the experimental researches in the modeling of the
haemodynamic shifts typical for the weightlessness (J.H Kilp., Heublen , 1984).

At the same time, some investigations demonstrated the negative
dynamics of the parameters of the accommodation and convergence, as well as the asthenopic
symptoms in cosmonauts even at the beginning of the flight (Y.P. Petrov, 1969). Those
symptoms were not progressed and some investigators did not obtain them at all and
followed the conclusion on the stability of the accommodation during the flight (O.O.
Riumin, 1980).Also, the studies of the color vision and color discrimination in cosmonauts
(A.L. Kitaev-Smik, 1969; L.P. Zverev., I.G. Ovechkin., O.O. Riumin, 1996) showed the
absence of the valuable variations of the mentioned parameters under the given condition.
The results of the contrast sensitivity examinations in the spaceship’s crew during the
flight demonstrated the 14-16 % decrement (A.P. Ginsburg, J. Vahderploeg, 1985) which
believed by the authors can’t be the reason of the reduction in functional condition of
the cosmonaut.

So, the analysis of the sources in the area from one hand let us
draw the conclusion that the variations of the main visual functions of the cosmonaut
during the flight are insignificant and are practically in the range of the physiological
norm. From the other hand, the range of the investigations in outer space was obviously
insufficient and was limited by the restricted set of the traditional methods.

PURPOSES

To develop the PC-based System of Connected Methods of the
functional condition investigations on the different levels of the visual system’s (VS)
organisation and to study variations of the cosmonaut’s VS parameters in the space
vehicle "Soyuz" and on the board of the orbital piloted complex "Mir".

Visual Acuity verification in achromatic (standard) and colored (red on blue, green on
purple and blue on yellow) tables.

Luminance Sensitivity Threshold (LST) detection in the Central Part of the Visual Field
(CPVF). Color Campimetry (“Ocular” program), CPVF range from -100 to +100,
red stimuli on achromatic background with luminance being equal to 0.1 cd/m2.

Rhythm's acquisition and reproduction’s dynamics after the complicated visual
stimulation. “Ocular-Rhythmic” program (Nesteruk L.I, Malova J.V., 1994). The Subject
was presented by 10 visual flashes of about 1 second interval between them (simple
rhythm); the flashes had changed stochastically the shape (square, circle), size (10 -
50), position (00 - 100 from the center on the screen).
The task was to remember the interval and to reproduce one by pressing any bottom on the
keyboard for 50 times.

"Simple" cognitive functions investigation after the visual stimulation of
varied spatial and temporal complexity. “Ocular-Gnostic” program. The Subject was
instructed to press a sum (0-9) of 3 numbers (0-3) presented stochastically on the screen
but equidistant from it’s center (50); the size of the stimuli was equal to 20;
the time of the numbers exposition varied from 1 to 0.2 seconds. The coefficient of the
correct answers in dependence of the exposition time was registered.

The Cosmonaut - Researcher Y. Baturin had performed visual tests
every day, except of the 1st day on the Station "Mir". Pre- and after-
expedition studies also were done including one right after the landing and during 1 week
of adaptation.

The processing of the data of the present investigation was
performed by the PC-package “Statistica”.

RESULTS

Figure 4. LST Integral
Coefficient.

Figure 5. Achromatic LST.

Figure 6. Colored LST.

It was shown for acuity of vision being stable during the experiment
(before, during and after the flight) except of the 9th day of the flight, when
only colored combinations (green on purple) demonstrated the negative dynamics for 50%,
10% and 10% in 3 examinations during the time interval of 8 hours.
The statistically significant achromatic and colored LSTs
(“Ocular”) both was found to be increased during the flight in comparison with ones
detected before and after the flight and was shown to have the different gradient in the
center and paracenter of the visual field (Fig.4, 5, 6). The LST’s maximum during the
flight (minimum sensitivity) was detected in 4-5 and 12-13 days. The LST’s minimum
(maximum sensitivity) was detected in 8-9 days of the flight, after which the LST’s
dynamics was negative till the end of the flight. After 1 week of adaptation (4, 6 and 8
days) the LST parameters reached the pre- flight level. That was not found the
statistically significant difference between LST parameters before and after the flight.

Rhythm's acquisition and reproduction dynamics (“Ocular-Rhythmic”)
after the complicated visual stimulation (Fig.7, 8, 9) demonstrated the maximum time’s
precision of reproduction (Mean Value) on the the 9th - 10th day of
the flight, which has the statistically significant difference in comparison with the
values before and after flight. At the same time the variability of reproduction (Standard
Deviation) was also maximal, and the stability (inverse to the Gradient) of those
parameters during the flight was minimal. It should be noted here that the Gradient was
negative except of 2-3th days of the flight (in the Spaceship), 15th day
(before landing) and at the end of the 1st week of adaptation after the flight.

"Simple" cognitive functions investigation
(“Ocular-Gnostic”) after the complicated visual stimulation (Fig. 10) was found to
have the maximal value of the coefficient in the flight (9th - 10th
day, Station “Mir”), not in the earth based ones. Interestingly, the statistically
significant difference of the coefficient was found only between ones before the flight
and during the presence of the cosmonaut on the Station. No significant difference was
found not only before and after the flight, but in the flight and after the flight too.

The results of the last three tests demonstrated the optimal values
of the parameters about the 9th day of the flight.

DISCUSSION

That was pointed out the data of the previous investigations on the
visual functions in the real and modeled cosmic flight had demonstrated the absence of the
principal shifts in the VS's functional condition of a cosmonaut. At the same time it is
believed to be obvious, that the factors of the cosmic flight should make a significant
influence on the VS. Those factors are known to cause the valuable changes in the
following physiological (and connected psychological) processes: the start of the
pathogenetic mechanisms in the general blood support system connected with haemodynamical
effects of the weightlessness and hypodynamia as well as with the variations of the
functional condition of the central and peripheral nervous system. Even the shape of the
eyeball is changing when the weightlessness (tended to be more spherical).

The subjective reports of the cosmonauts as well as one of the
cosmonaut - researcher Y. Baturin show sometimes the dramatic changes in vision.

The reason of the drawn contradictories might be seen in the
following:

the traditional methods of the study of the functional condition of the VS during the
cosmic flight oriented first to the examination of the accommodative - refractive system
of the eye;

the methods applied for the evaluation of the condition of the sensory and gnostic
levels are not sensitive and specific enough;

VS was not investigated as a whole functional subsystem of the organism under the
conditions of the cosmic flight;

the principal impossibility of the interpretation of the results of applied methods in
the correspondence to the levels of the VS’s organization.

The results of the present investigation show that an alternative
approach to the solution of the given problem can be found using the
"Ocular-complex" system, realizing psychophysical methods of investigation
correspondent to the different levels of the VS’s organization (Nesteruk L.I., 1992;
Nesteruk L.I., 1994; Nesteruk L.I, Shamshinova A.M., Endrichovsky S.E., 1995; Nesteruk
L.I., 1997).

The interesting fact demonstrated with the
"Ocular-complex" is the reliable difference in the functional condition of the
VS before, during and after the space flight. This difference could be characterized as a
negative dynamics during the space flight, which has a distinctive character showed by all
the 5 applied tests, correspondent to the various levels of the VS. The improvement of
major parameters about the 9th day of the flight is correspondence with the
data obtained on the cardio-vascular, respiratory and other functional systems (E.V.
Khrunov, L.S. Khachaturiantz, V.A. Popov, 1974; C.L. Fisher, J.Degianni, 1982). The
parameters of the tests during the 1st week of the after flight adaptation was
tended to rich the ones obtained before the flight, which is also supported with
investigations of other functional systems.

The analysis of the results shows the evidence on the high stability
of the visual acuity, the integrated parameter of the VS, to the influence of the damaging
factors in the space flight. The study of the LSTs (Color Campimetry) in the central and
paracentral parts of the VF on the achromatic and colored background let us reveal the
tendency to the reliable decrement of the light and color sensitivity during the flight in
comparison with the earth - based ones. It should be noted the presence of the 2 peaks of
LSTs (decrements of the sensitivity) in the 4-5 and the 12-13 days of the flight. The best
sensitivity (lowest LSTs) during the flight was registered in 8-9 days, which however were
lower than one before the flight.

The remarkable fact of the improving of the coefficient of the
“Simple” cognitive functions (“Ocular-Gnostic”) as well as it’s mounting to the
maximum value during the flight, in comparison with the earth - obtained one, might
appoint on the optimal level of the VS’s adaptation and on the best VS’s central part
performance.

Analyzing the dynamics of the mentioned parameters the assumption
could be drawn here on the some rhythmical, oscillatory character of the VS functioning
under the space flight conditions, manifested in the periodical variations in the
functional condition of the neuro- receptor and cortical levels of the VS.

Unfortunately, the insufficiency of the experimental material,
restricted by the time of the flight as well as the number of investigations, does not let
us to follow the mentioned tendency in time, and also to explain it from the point of the
haemodynamical shifts happened in the organism under the weightlessness condition.

CONCLUSIONS

The reliable variations of the functional condition of the VS of the cosmonaut were
detected before during and after the space flight by means of the
"Ocular-complex" program.

Five tests of the "Ocular-complex" demonstrate principally different character
of the parameter's variations, what can appoint on the detection by the complex of the
various properties (levels) of the VS.

The data of the "Ocular-complex" tests correlate with the ones obtained on the
other functional systems in the organism's adaptation during and after the flight.

The battery of the "Ocular-complex" tests can be recommended as the basic for
the evaluation of the VS's functional condition in outer space.

ASKNOWLEGEMENT

The first two authors would like to outline that the present
investigation was found to rich the auditorium because of the enthusiasm and the
intelligence of the Cosmonaut - Researcher Y. Baturin, who had continued to perform visual
test even in the extremal situations, when nobody believed it could be done.

Petrov Y.P.
The Influence of the Factors of the Space Flight on the Visual Functions. Physiology of
Vision in Norm and Extremal Conditions, AS USSR: 124-127. (in Rus.) 1969.

Riumin O.O.
The Influence of the Refractive Abilities of the Visual Analizator on the Reliability of
the Operators Functioning in the System of Visual Observation. Methodical and Technical
Aspects of the Experimental Psychophysiology. //Moscow. Nauka: 24-28. (in Rus.) 1980.